The Animal/Physiology Core (9002) provides support to all projects. Each project uses Fischer 344 rats that are acquired, housed, and maintained by the Core. The Core provides a centralized state of the art barrier facility for the housing of specific pathogen free rats used in the studies of the aged heart. The Core provides animal care that complies with standards of health for experimental animals required for gerontological studies, including a pathogen free environment, assessment of general health status on a daily basis, physical examination and measurements of body weight and renal function. The Core is located within dedicated space within the Animal Resource Facility of the Louis Stokes VAMC. The cardiac models supplied by the Core provide cardiac tissue to all of the projects. Cardiac tissue is obtained from hearts excised immediately following euthanasia for the study of the heart in the baseline state; and from isolated, buffer perfused heart experiments. Heart perfusion protocols include time control perfusions, ischemia alone, and reperfusion periods of up to 120 minutes. Two isolated perfused heart models have been employed, the Langendorff model and the working heart model. The studies proposed in the revised application use the two current models as well as new approaches. The Core will perfuse isolated hearts to prepare tissue for the isolation of cardiac myocytes by 0003. Core personnel will collaborate with 0003 to bring the model of in vivo cardiac gene transfer to the Core. The Core will facilitate the Inter-project Collaborative Studies: Amytal-Intervention and the Glutaredoxin-Intervention. These studies maximize sharing of tissues among projects. In addition, the Core co-ordinates interactions among the four projects to share tissues from untreated rats in the baseline state prior to ischemia, following ischemia, and following ischemia and reperfusion. Cardiac tissue is provided to core-9004 for the isolation of cardiac mitochondria and for analysis by light and electron microscopy. Additional cardiac tissue is provided directly to the projects for biochemical and molecular studies. Excess cardiac tissue samples are catalogued and stored for future use. Experiments are entered into a common database available via network to all projects.